//
//  TextView.swift
//  MVMCoreUI
//
//  Created by Kevin Christiano on 4/1/20.
//  Copyright © 2020 Verizon Wireless. All rights reserved.
//

import UIKit


@objc open class TextView: UITextView, UITextViewDelegate, MVMCoreViewProtocol {
    //--------------------------------------------------
    // MARK: - Properties
    //--------------------------------------------------
    
    open var model: MoleculeModelProtocol?
    
    private var initialSetupPerformed = false
    
    /// If true then text textView is currently displaying the stored placeholder text as there is not content to display.
    public var isShowingPlaceholder: Bool = false {
        didSet { textViewModel?.showsPlaceholder = isShowingPlaceholder }
    }
    
    /// Set to true to hide the blinking textField cursor.
    public var hideBlinkingCaret = false
    
    public var textViewModel: TextViewModel? {
        return model as? TextViewModel
    }
    
    //--------------------------------------------------
    // MARK: - Drawing Properties
    //--------------------------------------------------
    
    private(set) var fieldState: FieldState = .original {
        didSet (oldState) {
            // Will not update if new state is the same as old.
            if fieldState != oldState {
                DispatchQueue.main.async { [weak self] in
                    guard let self = self else { return }
                    
                    self.fieldState.setStateUI(for: self)
                }
            }
        }
    }
    
    /// Determines if the top, left, and right borders should be drawn.
    private var hideBorders = false
    
    public var borderStrokeColor: UIColor = .mvmCoolGray3
    public var bottomStrokeColor: UIColor = .mvmBlack
    private var borderPath: UIBezierPath = UIBezierPath()
    private var bottomPath: UIBezierPath = UIBezierPath()
    
    //--------------------------------------------------
    // MARK: - Property Observers
    //--------------------------------------------------
    
    private var _isEnabled: Bool = true
    private var _showError: Bool = false
    private var _isSelected: Bool = false
    
    public var isEnabled: Bool {
        get { return _isEnabled }
        set (enabled) {
            
            _isEnabled = enabled
            _isSelected = false
            _showError = false
            
            fieldState = enabled ? .original : .disabled
        }
    }
    
    public var showError: Bool {
        get { return _showError }
        set (error) {
            
            _showError = error
            _isEnabled = true
            _isSelected = false
            
            fieldState = error ? .error : .original
        }
    }
    
    public var isSelected: Bool {
        get { return _isSelected }
        set (selected) {
            
            _isSelected = selected
            _isEnabled = true
            
            if _showError {
                fieldState = selected ? .selectedError : .error
            } else {
                fieldState = selected ? .selected : .original
            }
        }
    }
    
    //--------------------------------------------------
    // MARK: - Delegate
    //--------------------------------------------------
    
    /// Holds a reference to the delegating class so this class can internally influence the TextField behavior as well.
    public weak var didDeleteDelegate: TextInputDidDeleteProtocol?
    
    /// Holds a reference to the delegating class so this class can internally influence the TextField behavior as well.
    private weak var proprietorTextDelegate: UITextViewDelegate?
    
    /// If you're using a ViewController, you must set this to it.
    public weak var uiTextViewDelegate: UITextViewDelegate? {
        get { return delegate }
        set {
            delegate = self
            proprietorTextDelegate = newValue
        }
    }
    
    var delegateObject: MVMCoreUIDelegateObject?
    
    //--------------------------------------------------
    // MARK: - Constraint
    //--------------------------------------------------
    
    public var heightConstraint: NSLayoutConstraint?
    
    //--------------------------------------------------
    // MARK: - Initialization
    //--------------------------------------------------
    
    public override init(frame: CGRect, textContainer: NSTextContainer?) {
        super.init(frame: .zero, textContainer: nil)
        initialSetup()
    }
    
    public convenience init() {
        self.init(frame: .zero, textContainer: nil)
    }
    
    public required init?(coder: NSCoder) {
        super.init(coder: coder)
        initialSetup()
    }
    
    convenience init(delegate: UITextViewDelegate) {
        self.init(frame: .zero, textContainer: nil)
        self.delegate = delegate
    }
    
    //--------------------------------------------------
    // MARK: - Lifecycle
    //--------------------------------------------------
    
    public func initialSetup() {
        
        if !initialSetupPerformed {
            tintColor = .mvmBlack
            initialSetupPerformed = true
            setupView()
        }
    }
    
    open func updateView(_ size: CGFloat) {
        
        setNeedsDisplay()
    }
    
    /// Will be called only once.
    open func setupView() {
        
        translatesAutoresizingMaskIntoConstraints = false
        initialConfiguration()
    }
    
    public func initialConfiguration() {
        
        insetsLayoutMarginsFromSafeArea = false
        showsVerticalScrollIndicator = false
        showsHorizontalScrollIndicator = false
        isSecureTextEntry = false
        textContainerInset = UIEdgeInsets(top: Padding.Three, left: Padding.Three, bottom: Padding.Three, right: Padding.Three)
        backgroundColor = .mvmWhite
        clipsToBounds = true
        smartQuotesType = .no
        smartDashesType = .no
        smartInsertDeleteType = .no
        font = textViewModel?.fontStyle.getFont()
        isEditable = true
        isOpaque = false
    }
    
    open func reset() {
        
        text = ""
        inputAccessoryView?.removeFromSuperview()
        initialConfiguration()
    }
    
    open override func layoutSubviews() {
        super.layoutSubviews()
        
        setNeedsDisplay()
    }
    
    //--------------------------------------------------
    // MARK: - Draw
    //--------------------------------------------------
    
    /// This handles the top, left, and right border lines.
    open override func draw(_ rect: CGRect) {
        super.draw(rect)
        
        borderPath.removeAllPoints()
        bottomPath.removeAllPoints()
        
        if !hideBorders {
            // Brings the other half of the line inside the view to prevent line cropping.
            let origin = bounds.origin
            let size = frame.size
            let insetLean: CGFloat = 0.5
            borderPath.lineWidth = 1
            
            // Drawing begins and ends from the bottom left.
            borderPath.move(to: CGPoint(x: origin.x + insetLean, y: origin.y + size.height))
            borderPath.addLine(to: CGPoint(x: origin.x + insetLean, y: origin.y + insetLean))
            borderPath.addLine(to: CGPoint(x: origin.x + size.width - insetLean, y: origin.y + insetLean))
            borderPath.addLine(to: CGPoint(x: origin.x + size.width - insetLean, y: origin.y + size.height))
            
            borderStrokeColor.setStroke()
            borderPath.stroke()
            
            let lineWidth: CGFloat = showError || isSelected ? 4 : 1
            bottomPath.lineWidth = lineWidth
            bottomPath.move(to: CGPoint(x: origin.x + size.width, y: origin.y + size.height - (lineWidth / 2)))
            bottomPath.addLine(to: CGPoint(x: origin.x, y: origin.y + size.height - (lineWidth / 2)))
            
            bottomStrokeColor.setStroke()
            bottomPath.stroke()
        }
    }
    
    //--------------------------------------------------
    // MARK: - Draw States
    //--------------------------------------------------
    
    public enum FieldState {
        case original
        case error
        case selectedError
        case selected
        case disabled
        
        public func setStateUI(for inputField: TextView) {
            
            switch self {
            case .original:
                inputField.originalUI()
                
            case .error:
                inputField.errorUI()
                
            case .selectedError:
                inputField.selectedErrorUI()
                
            case .selected:
                inputField.selectedUI()
                
            case .disabled:
                inputField.disabledUI()
            }
            
            inputField.setNeedsDisplay()
        }
    }
    
    open func originalUI() {
        
        isEditable = textViewModel?.editable ?? true
        isUserInteractionEnabled = true
        hideBorders = textViewModel?.hideBorders ?? false
        borderStrokeColor = .mvmCoolGray3
        bottomStrokeColor = .mvmBlack
        textColor = isShowingPlaceholder ? textViewModel?.placeholderTextColor.uiColor : textViewModel?.enabledTextColor.uiColor
    }
    
    open func errorUI() {
        
        isEditable = textViewModel?.editable ?? true
        isUserInteractionEnabled = true
        hideBorders = textViewModel?.hideBorders ?? false
        borderStrokeColor = .mvmOrange
        bottomStrokeColor = .mvmOrange
        textColor = textViewModel?.enabledTextColor.uiColor
    }
    
    open func selectedErrorUI() {
        
        isEditable = textViewModel?.editable ?? true
        isUserInteractionEnabled = true
        hideBorders = textViewModel?.hideBorders ?? false
        borderStrokeColor = .mvmBlack
        bottomStrokeColor = .mvmOrange
        textColor = textViewModel?.enabledTextColor.uiColor
    }
    
    open func selectedUI() {
        
        isEditable = textViewModel?.editable ?? true
        isUserInteractionEnabled = true
        hideBorders = textViewModel?.hideBorders ?? false
        borderStrokeColor = .mvmBlack
        bottomStrokeColor = .mvmBlack
        textColor = textViewModel?.enabledTextColor.uiColor
    }
    
    open func disabledUI() {
        
        isEditable = textViewModel?.editable ?? false
        isUserInteractionEnabled = false
        hideBorders = textViewModel?.hideBorders ?? false
        borderStrokeColor = .mvmCoolGray3
        bottomStrokeColor = .mvmCoolGray3
        textColor = textViewModel?.disabledTextColor.uiColor
    }
    
    //--------------------------------------------------
    // MARK: - Methods
    //--------------------------------------------------
    
    /// Alters the blinking caret line as per design standards.
    open override func caretRect(for position: UITextPosition) -> CGRect {
        
        if hideBlinkingCaret {
            return .zero
        }
        
        let caretRect = super.caretRect(for: position)
        return CGRect(origin: caretRect.origin, size: CGSize(width: 1, height: caretRect.height))
    }
    
    open override func deleteBackward() {
        super.deleteBackward()
        didDeleteDelegate?.textInputDidDelete()
    }
    
    public func setTextAppearance() {
        
        if isShowingPlaceholder {
            setTextContentTraits()
        }
    }
    
    public func setPlaceholderIfAvailable() {
        
        if let placeholder = textViewModel?.placeholder, !placeholder.isEmpty && text.isEmpty {
            setPlaceholderContentTraits()
        }
    }
    
    public func setTextContentTraits() {
        
        isShowingPlaceholder = false
        text = ""
        font = textViewModel?.fontStyle.getFont()
        textColor = textViewModel?.enabledTextColor.uiColor
    }
    
    public func setPlaceholderContentTraits() {
        
        isShowingPlaceholder = true
        textColor = textViewModel?.placeholderTextColor.uiColor
        font = textViewModel?.placeholderFontStyle.getFont()
        text = textViewModel?.placeholder
    }
    
    //--------------------------------------------------
    // MARK: - UITextViewDelegate
    //--------------------------------------------------
    
    @objc public func textViewShouldBeginEditing(_ textView: UITextView) -> Bool {
        
        return proprietorTextDelegate?.textViewShouldBeginEditing?(textView) ?? true
    }
    
    @objc public func textViewDidBeginEditing(_ textView: UITextView) {
        
        setTextAppearance()
        isSelected = true
        proprietorTextDelegate?.textViewDidBeginEditing?(textView)
    }
    
    @objc public func textView(_ textView: UITextView, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool {
        
        return proprietorTextDelegate?.textView?(textView, shouldChangeTextIn: range, replacementText: text) ?? true
    }
    
    @objc public func textViewDidChange(_ textView: UITextView) {
        
        textViewModel?.text = textView.text
        proprietorTextDelegate?.textViewDidChange?(textView)
    }
    
    @objc public func textViewShouldEndEditing(_ textView: UITextView) -> Bool {
        
        return proprietorTextDelegate?.textViewShouldEndEditing?(textView) ?? true
    }
    
    @objc public func textViewDidEndEditing(_ textView: UITextView) {
        
        setPlaceholderIfAvailable()
        isSelected = false
        proprietorTextDelegate?.textViewDidEndEditing?(textView)
    }
}

// MARK:- MoleculeViewProtocol
extension TextView: MoleculeViewProtocol {
    
    open func set(with model: MoleculeModelProtocol, _ delegateObject: MVMCoreUIDelegateObject?, _ additionalData: [AnyHashable: Any]?) {
        self.model = model
        self.delegateObject = delegateObject
        
        if let color = model.backgroundColor?.uiColor {
            backgroundColor = color
        }
        
        guard let model = model as? TextViewModel else { return }
        
        heightConstraint?.isActive = false
        if let height = model.height {
            heightConstraint = heightAnchor.constraint(equalToConstant: height)
            heightConstraint?.isActive = true
        }
        
        isEditable = model.editable
        textAlignment = model.textAlignment
        textColor = model.enabledTextColor.uiColor
        hideBorders = model.hideBorders
        text = model.text
        uiTextViewDelegate = delegateObject?.uiTextViewDelegate
        
        if let accessibilityText = model.accessibilityText {
            accessibilityLabel = accessibilityText
        }
        
        switch model.type {
        case .secure, .password:
            isSecureTextEntry = true
        case .number:
            keyboardType = .numberPad
        case .email:
            keyboardType = .emailAddress
        default:
            break
        }
        
        font = model.fontStyle.getFont()
        setPlaceholderIfAvailable()
        
        if isEditable {
            FormValidator.setupValidation(for: model, delegate: delegateObject?.formHolderDelegate)
            MVMCoreUICommonViewsUtility.addDismissToolbar(to: self, delegate: delegateObject?.uiTextViewDelegate)
            
            if (model.selected ?? false) && !model.wasInitiallySelected {
                model.wasInitiallySelected = true
                DispatchQueue.main.async {
                    self.becomeFirstResponder()
                }
            }
        }
        
        if !model.enabled {
            isEnabled = false
        }
    }
}